Some of these are sets and some are bricks. Sorry if the quality is bad, I can't get any other pictures.
Please note: 3 and 4 seems to be from the same build, although I cannot fully verify that. Thanks in advance!
Bionicle piece ???
Part #98141 Minifigure, Weapon Crescent Blade, Serrated with Bar, with an updated and correct answer provided by site member Phil B.
3 + 4) Hails from Set #76109 Quantum Realm Explorers.
The yellowed outlined pieces in 3 and 4 is Part #17485 Brick, Round 2 x 2 with Pin Holes.
HERE's a Youtube speed build on the piece breakdown/buildup of this design look you're interested in.